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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '01e8f9f5879a2f6b71b986e8f791485fd0faf4c39c7573270947429da1de5cd2' 
  AND token = 'YnOAdD9d3EYiNVi3lLbWznqsRk/Hh1eKJ2XY5NLzN2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}